use nu_engine::{ClosureEval, ClosureEvalOnce, command_prelude::*};
use nu_protocol::ast::PathMember;
#[derive(Clone)]
pub struct Update;
impl Command for Update {
fn name(&self) -> &str {
"update"
}
fn signature(&self) -> Signature {
Signature::build("update")
.input_output_types(vec![
(Type::record(), Type::record()),
(Type::table(), Type::table()),
(
Type::List(Box::new(Type::Any)),
Type::List(Box::new(Type::Any)),
),
])
.required(
"field",
SyntaxShape::CellPath,
"The name of the column to update.",
)
.required(
"replacement value",
SyntaxShape::Any,
"The new value to give the cell(s), or a closure to create the value.",
)
.allow_variants_without_examples(true)
.category(Category::Filters)
}
fn description(&self) -> &str {
"Update an existing column to have a new value."
}
fn extra_description(&self) -> &str {
"When updating a column, the closure will be run for each row, and the current row will be passed as the first argument. \
Referencing `$in` inside the closure will provide the value at the column for the current row.
When updating a specific index, the closure will instead be run once. The first argument to the closure and the `$in` value will both be the current value at the index."
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
update(engine_state, stack, call, input)
}
fn examples(&self) -> Vec<Example> {
vec![
Example {
description: "Update a column value",
example: "{'name': 'nu', 'stars': 5} | update name 'Nushell'",
result: Some(Value::test_record(record! {
"name" => Value::test_string("Nushell"),
"stars" => Value::test_int(5),
})),
},
Example {
description: "Use a closure to alter each value in the 'authors' column to a single string",
example: "[[project, authors]; ['nu', ['Andrés', 'JT', 'Yehuda']]] | update authors {|row| $row.authors | str join ',' }",
result: Some(Value::test_list(vec![Value::test_record(record! {
"project" => Value::test_string("nu"),
"authors" => Value::test_string("Andrés,JT,Yehuda"),
})])),
},
Example {
description: "Implicitly use the `$in` value in a closure to update 'authors'",
example: "[[project, authors]; ['nu', ['Andrés', 'JT', 'Yehuda']]] | update authors { str join ',' }",
result: Some(Value::test_list(vec![Value::test_record(record! {
"project" => Value::test_string("nu"),
"authors" => Value::test_string("Andrés,JT,Yehuda"),
})])),
},
Example {
description: "Update a value at an index in a list",
example: "[1 2 3] | update 1 4",
result: Some(Value::test_list(vec![
Value::test_int(1),
Value::test_int(4),
Value::test_int(3),
])),
},
Example {
description: "Use a closure to compute a new value at an index",
example: "[1 2 3] | update 1 {|i| $i + 2 }",
result: Some(Value::test_list(vec![
Value::test_int(1),
Value::test_int(4),
Value::test_int(3),
])),
},
]
}
}
fn update(
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let head = call.head;
let cell_path: CellPath = call.req(engine_state, stack, 0)?;
let replacement: Value = call.req(engine_state, stack, 1)?;
match input {
PipelineData::Value(mut value, metadata) => {
if let Value::Closure { val, .. } = replacement {
match (cell_path.members.first(), &mut value) {
(Some(PathMember::String { .. }), Value::List { vals, .. }) => {
let mut closure = ClosureEval::new(engine_state, stack, *val);
for val in vals {
update_value_by_closure(
val,
&mut closure,
head,
&cell_path.members,
false,
)?;
}
}
(first, _) => {
update_single_value_by_closure(
&mut value,
ClosureEvalOnce::new(engine_state, stack, *val),
head,
&cell_path.members,
matches!(first, Some(PathMember::Int { .. })),
)?;
}
}
} else {
value.update_data_at_cell_path(&cell_path.members, replacement)?;
}
Ok(value.into_pipeline_data_with_metadata(metadata))
}
PipelineData::ListStream(stream, metadata) => {
if let Some((
&PathMember::Int {
val,
span: path_span,
..
},
path,
)) = cell_path.members.split_first()
{
let mut stream = stream.into_iter();
let mut pre_elems = vec![];
for idx in 0..=val {
if let Some(v) = stream.next() {
pre_elems.push(v);
} else if idx == 0 {
return Err(ShellError::AccessEmptyContent { span: path_span });
} else {
return Err(ShellError::AccessBeyondEnd {
max_idx: idx - 1,
span: path_span,
});
}
}
let value = pre_elems.last_mut().expect("one element");
if let Value::Closure { val, .. } = replacement {
update_single_value_by_closure(
value,
ClosureEvalOnce::new(engine_state, stack, *val),
head,
path,
true,
)?;
} else {
value.update_data_at_cell_path(path, replacement)?;
}
Ok(pre_elems
.into_iter()
.chain(stream)
.into_pipeline_data_with_metadata(
head,
engine_state.signals().clone(),
metadata,
))
} else if let Value::Closure { val, .. } = replacement {
let mut closure = ClosureEval::new(engine_state, stack, *val);
let stream = stream.map(move |mut value| {
let err = update_value_by_closure(
&mut value,
&mut closure,
head,
&cell_path.members,
false,
);
if let Err(e) = err {
Value::error(e, head)
} else {
value
}
});
Ok(PipelineData::ListStream(stream, metadata))
} else {
let stream = stream.map(move |mut value| {
if let Err(e) =
value.update_data_at_cell_path(&cell_path.members, replacement.clone())
{
Value::error(e, head)
} else {
value
}
});
Ok(PipelineData::ListStream(stream, metadata))
}
}
PipelineData::Empty => Err(ShellError::IncompatiblePathAccess {
type_name: "empty pipeline".to_string(),
span: head,
}),
PipelineData::ByteStream(stream, ..) => Err(ShellError::IncompatiblePathAccess {
type_name: stream.type_().describe().into(),
span: head,
}),
}
}
fn update_value_by_closure(
value: &mut Value,
closure: &mut ClosureEval,
span: Span,
cell_path: &[PathMember],
first_path_member_int: bool,
) -> Result<(), ShellError> {
let value_at_path = value.follow_cell_path(cell_path)?;
let arg = if first_path_member_int {
value_at_path.as_ref()
} else {
&*value
};
let new_value = closure
.add_arg(arg.clone())
.run_with_input(value_at_path.into_owned().into_pipeline_data())?
.into_value(span)?;
value.update_data_at_cell_path(cell_path, new_value)
}
fn update_single_value_by_closure(
value: &mut Value,
closure: ClosureEvalOnce,
span: Span,
cell_path: &[PathMember],
first_path_member_int: bool,
) -> Result<(), ShellError> {
let value_at_path = value.follow_cell_path(cell_path)?;
let arg = if first_path_member_int {
value_at_path.as_ref()
} else {
&*value
};
let new_value = closure
.add_arg(arg.clone())
.run_with_input(value_at_path.into_owned().into_pipeline_data())?
.into_value(span)?;
value.update_data_at_cell_path(cell_path, new_value)
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_examples() {
use crate::test_examples;
test_examples(Update {})
}
}